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powerpc/security: split branch cache flush toggle from code patching

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Branch cache flushing code patching has inter-dependencies on both the
link stack and the count cache flushing state.

To make the code clearer and to separate the link stack and count
cache handling, split the "toggle" (setting up variables and printing
enable/disable) from the code patching.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Always print something, even if the flush is disabled]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200609070610.846703-5-npiggin@gmail.com
This commit is contained in:
Nicholas Piggin 2020-06-09 17:06:07 +10:00 committed by Michael Ellerman
parent 1afe00c74f
commit c0036549a9
1 changed files with 54 additions and 46 deletions
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100
arch/powerpc/kernel/security.c
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@ -427,61 +427,69 @@ static __init int stf_barrier_debugfs_init(void)
device_initcall(stf_barrier_debugfs_init);
#endif /* CONFIG_DEBUG_FS */
static void no_count_cache_flush(void)
static void update_branch_cache_flush(void)
{
count_cache_flush_type = BRANCH_CACHE_FLUSH_NONE;
pr_info("count-cache-flush: flush disabled.\n");
#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
// This controls the branch from guest_exit_cont to kvm_flush_link_stack
if (link_stack_flush_type == BRANCH_CACHE_FLUSH_NONE) {
patch_instruction_site(&patch__call_kvm_flush_link_stack,
ppc_inst(PPC_INST_NOP));
} else {
patch_branch_site(&patch__call_kvm_flush_link_stack,
(u64)&kvm_flush_link_stack, BRANCH_SET_LINK);
}
#endif
// This controls the branch from _switch to flush_branch_caches
if (count_cache_flush_type == BRANCH_CACHE_FLUSH_NONE &&
link_stack_flush_type == BRANCH_CACHE_FLUSH_NONE) {
patch_instruction_site(&patch__call_flush_branch_caches,
ppc_inst(PPC_INST_NOP));
} else {
patch_branch_site(&patch__call_flush_branch_caches,
(u64)&flush_branch_caches, BRANCH_SET_LINK);
// If we just need to flush the link stack, early return
if (count_cache_flush_type == BRANCH_CACHE_FLUSH_NONE) {
patch_instruction_site(&patch__flush_link_stack_return,
ppc_inst(PPC_INST_BLR));
// If we have flush instruction, early return
} else if (count_cache_flush_type == BRANCH_CACHE_FLUSH_HW) {
patch_instruction_site(&patch__flush_count_cache_return,
ppc_inst(PPC_INST_BLR));
}
}
}
static void toggle_branch_cache_flush(bool enable)
{
if (!security_ftr_enabled(SEC_FTR_FLUSH_COUNT_CACHE) &&
!security_ftr_enabled(SEC_FTR_FLUSH_LINK_STACK))
enable = false;
if (!enable || !security_ftr_enabled(SEC_FTR_FLUSH_COUNT_CACHE)) {
if (count_cache_flush_type != BRANCH_CACHE_FLUSH_NONE)
count_cache_flush_type = BRANCH_CACHE_FLUSH_NONE;
pr_info("count-cache-flush: flush disabled.\n");
} else {
if (security_ftr_enabled(SEC_FTR_BCCTR_FLUSH_ASSIST)) {
count_cache_flush_type = BRANCH_CACHE_FLUSH_HW;
pr_info("count-cache-flush: hardware flush enabled.\n");
} else {
count_cache_flush_type = BRANCH_CACHE_FLUSH_SW;
pr_info("count-cache-flush: software flush enabled.\n");
}
}
if (!enable || !security_ftr_enabled(SEC_FTR_FLUSH_LINK_STACK)) {
if (link_stack_flush_type != BRANCH_CACHE_FLUSH_NONE)
link_stack_flush_type = BRANCH_CACHE_FLUSH_NONE;
if (!enable) {
patch_instruction_site(&patch__call_flush_branch_caches,
ppc_inst(PPC_INST_NOP));
#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
patch_instruction_site(&patch__call_kvm_flush_link_stack,
ppc_inst(PPC_INST_NOP));
#endif
pr_info("link-stack-flush: flush disabled.\n");
link_stack_flush_type = BRANCH_CACHE_FLUSH_NONE;
no_count_cache_flush();
return;
} else {
link_stack_flush_type = BRANCH_CACHE_FLUSH_SW;
pr_info("link-stack-flush: software flush enabled.\n");
}
// This enables the branch from _switch to flush_branch_caches
patch_branch_site(&patch__call_flush_branch_caches,
(u64)&flush_branch_caches, BRANCH_SET_LINK);
#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
// This enables the branch from guest_exit_cont to kvm_flush_link_stack
patch_branch_site(&patch__call_kvm_flush_link_stack,
(u64)&kvm_flush_link_stack, BRANCH_SET_LINK);
#endif
pr_info("link-stack-flush: software flush enabled.\n");
link_stack_flush_type = BRANCH_CACHE_FLUSH_SW;
// If we just need to flush the link stack, patch an early return
if (!security_ftr_enabled(SEC_FTR_FLUSH_COUNT_CACHE)) {
patch_instruction_site(&patch__flush_link_stack_return,
ppc_inst(PPC_INST_BLR));
no_count_cache_flush();
return;
}
if (!security_ftr_enabled(SEC_FTR_BCCTR_FLUSH_ASSIST)) {
count_cache_flush_type = BRANCH_CACHE_FLUSH_SW;
pr_info("count-cache-flush: software flush enabled.\n");
return;
}
patch_instruction_site(&patch__flush_count_cache_return, ppc_inst(PPC_INST_BLR));
count_cache_flush_type = BRANCH_CACHE_FLUSH_HW;
pr_info("count-cache-flush: hardware flush enabled.\n");
update_branch_cache_flush();
}
void setup_count_cache_flush(void)